Heretofore, transformers in commercial settings half typically comprised a transformer core assembly having a primary and secondary windings coupled with a laminated iron core element, typically in an E-shaped configuration. During operation, essentially all of the energy dissipated in a conventional transformer appears as heat that is generated primarily by the transformer windings and core. Such heat increases the temperature of the windings and core, and thus, reduces the efficiency of the transformer. To operate the transformer in the safe temperature limit for the rated output capacity, the heat generated in the transformer in the form of losses must be carried away to the cooling medium which is air.
Prior attempts have been made in this field without adequately resolving the above-mentioned problems. For example, Spindler, U.S. Pat. No. 2,947,957, provides a transformer with spaced metallic cooling fins for thermally conducting heat generated by the core and coil. The cooling fins are secured to the core of the transformer via retaining screws. When the transformer is assembled, the entire assembly is dipped in a thermally conductive potting compound to increase the ruggedness and dissipation of heat from the windings. This design, however, is larger than conventional transformer designs with its protruding fins while not completely solving the problems associated with heat losses.
Other prior transformer designs have attempted to address the heat dissipation deficiencies generally associated with the prior art systems discussed above. One such attempt is found in Herbst, U.S. Pat. No. 2,948,930, for a heat conductive potting compound which is used to conduct heat from a transformer. This system, like the others discussed above, fails to satisfactorily overcome the operating deficiencies noted above, and further represents a somewhat bulky transformer design.
Still other designs have employed the use of a premolded shell that surrounds the internal components of the transformer. In particular, the shell is placed over the transformer coil and is glued to the transformer core. The shell is then filled with a liquid epoxy resin that is heated and cured. The premolded shell of these configurations, however, creates a heat dissipation interface that actually interferes with the heat transfer of the core and windings. Accordingly, these designs likewise fail to totally address the heat transfer requirements of the core and windings of the transfer.